Apparatus for protecting electrical circuits



(No Model.)

J.M.0RAM. APPARATUS FOR PROTECTING ELECTRICAL GIRGUITS. No. 552,542. Patented Jan. '7, 1896.

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' WITNESSES: A MQIP L z By '5 Atzomey I /M% df 7 ANDREW BBRAHAMA FHOT0-LITHC WASHINGTON. BL.

UNTTED STATES PATENT @rrrcn'.

JOHN M. ORAM, OF DALLAS, TEXAS.

APPARATUS FOR PROTECTING ELECTRICAL CIRCUITS.

SPECIFICATION forming part of Letters Patent No. 552,542, dated January '7, 1896.

Application filed J 11119 4, 1895. Serial No. 551,642. (No model.)

To all whom it may concern.-

Be it known that 1, JOHN M. ORAM, a citizen of the United'States, residing at Dallas, in the county of Dallas, State of Texas, have invented certain new and useful Improvements in Apparatus for Protecting Electrical Circuits Against Unauthorized Interference, of which the following is a specification.

The object of my inventionis to provide for sounding an alarm or giving suitable indication whenever the normal operation of an electrical circuit is changed from a predetermined condition.

My invention is an improvement upon a method of and apparatus for protecting electrical circuits, such as is described and illustrated in Letters Patent of the United States issued upon my application, and numbered 537,932, dated April 23, 1895. In said Letters Patent there is a protected structure, such as a safe or vault, surrounded with a series of convolutions of an electrical conductor, such as a tin-foil strip, included in circuit with an artificial resistance. A sheet of foil or other suitable conductor is placed near to but insulated from said strip and electrically connected to said circuit ata point upon the side of said artificial resistance opposite said foilstrip, the arrangement being such that the breaking of the foil-strip breaks the circuit, and the electrical connection of the strip and sheet operates to short-circuit the artificial resistance. In addition to this I have there provided for a continuously-operating signaltransmitter, located within the protected structure, and for changing the signal so transmitted according to a predetermined plan or pattern, varying said signal from time to time as regards the intervals or charactor of the signal,or both,in a manner known only to the watchman stationed near an electromagnetic receiving-instrument at a central point or station. The signal-transmitter operates by varying the strength of line-current and the receiving-instrument operates a local circuit and alarm responding to four conditions of the main circuit as follows: first, line open, no current; second, line closed, all resistance out, current strength a maximum; third, line closed, all resistance in, current strength a minim um; fourth, line closed, smaller section of resistance cutout, current strength intermediate. In the above-described patented method and apparatus the alarm or indication of interference depends upon an interruption of or departure from the predetermined continuous succession of signals or normal conditions, and it is necessary for the watchman to keep continuously on the alert ;to detect any such variation in the recorded or received signals and conditions. Now my present improvements are designed to render continuous watching in order to detect variations from the described signals and conditions unnecessary, and to provide for sounding an alarm or giving any suitable indication when any variation from normal conditionsor predetermined signals occur, and at such times only.

My improvements, therefore, consist in combining with a protected structure, arranged substantially as described, an electrical circuit, an alarm or indicator, a continuously-operating signal-transmitter at the protected structure operating to aifect or influence the alarm or indicator, and a second or duplicate continuously-operating signaltransmitter located at the watchmans station, operating in unison with thefirst-namedsignal transmitter to affect the alarm or indicator equally and oppositely as regards the first-named transmitter, whereby a signal is sounded or an alarm given only when the two transmitters are out of unison or when one is changed, varied, or interfered with in an un authorized manner.

As herein shown and described by me, the first transmitter operates to make and break the alarm or indicator circuit, and the second transmitter operates in unison to make and break said circuitthat is to say, when one transmitter makes the alarm-circuit the second transmitter, if in unison, breaks said circuit, and vice versa, and any failure in approximately or substantially accurate corre spondence or unison results in sounding or indicating such failure.

. The accompanying drawings illustrate my invention.

Figure 1 is a complete schematic drawing.

of the construction and arrangement of the circuit and apparatus. Fig. 2 is a top plan Fig. 3 shows the various positions of the relay contactpoints when influenced by the various conditions of the main line.

S is a safe or protected structure, upon the outside of which are a convoluted strip of conducting material of any suitable character, such as tin-foil s, and a sheet of conducting material, such as tin-foil 10, arranged in a parallel plane, separated from the strip 3 by a sheet of insulating material i.

The electromagnet E at a central station is in a main circuit 3 at with the strip of foil 8 and main battery B. At the protected station there is an artificial resistance in two sections R R, normally in the main circuit. The convoluted strip 8 is in circuit between the resistance and the magnet E, and a point in said circuit upon the opposite side of said resistance is electrically connected to the sheet of foil 10 by conductor 5. It results from this that when strip 5 and sheet w are in any manner electrically connected resistances R and R are cut out and a maximum currentsay a current of four units-flows in the main circuit. To these variations magnet E always responds, operating alarm 0 through local circuit 29 b c 31, one branch of the fixed double contact 21 22 and point 23 on the rotary armature 18, the extra contactsprings'19 and 20 yielding to allow local connection to be made, as shown in the two first diagrams of Fig. 3, where C equals 0 and C equals 4.

The transmitter X located within the protected structure S consists of a series of wheels or disks upon an arbor, to which a mo-v tor imparts uniform movement of rotation. The arrangement and succession of the wheels upon the arbor may be changed at will, and the periphery of the wheels is notched or provided with teeth in groups, separated by spaces or arranged in any suitable characteristic manner. An arm a, carrying a circuitchan'ging device, is in position to engage with the periphery of the notched wheels, one after another, the change from one wheel to another being performed automatically and periodically, as described in my prior-granted patent above referred to. The circuit-closer shown in Fig. 1 consists of two pivoted c011- tact-levers 8 and 9. 10 is a limiting-stop for the lever 8, and 13 is a contact on the lever 8 in position to engage with the contact 9. A foot let on the arm 9 rides upon the periphery of the toothed wheels. The transmitter X operates when a tooth or projection passes under the projection let on the arm 9 to shortcircuit the resistance R, and the armature local point 23 011 magnet E takes up its position in contact with spring-contact 19. \V hen circuit-closing levers 8 and 9 of transmitter X are out of contact R is in circuit and local point 23, under the influence of retractingspring q, makes contact with spring-contact 20. These two positions are shown in the third and fourth diagrams of Fig. 3, where 0 equals 2 and C equals 1.

At the watchmans station there is a transmitter Y, exactly like transmitter X, and capable of the same changes as regards the character and arrangement of the signal transmitted. X and Y operate simultaneously and their signals are transmitted in substantial unison. Both are operated by a spring motor and are in reality ehronometers, although I may employ any known form of motor and may maintain synchronism and unison in any known or suitable manner.

The spring-contact 19 is a terminal of localcircuit branch 33, and spring-contact 20 is a terminal of localcircuit branch 32, both branches being connected with the alarm by conductor 28. The transmitter Y has a circuit-breaker composed of pivoted levers and 3G. 37 is a limit-stop for 36, and 38 is its contact-point. One end of 35 makes contact with contact-stop 34. Its opposite end is furnished with a curved foot 39, riding on the periphery of the transmitting-wheels Y. On the surface of foot 39, midway its ends, is a tooth 40. When 39 rides on the tooth of Y, circuit is open at 3 1. hen a tooth of the wheel at Y engages tooth 40, circuit is closed at 38. At all other times it is open.

The operation is as follows: hen the circuit is broken, or when the artificial resist-- ance R R is cut out, the contact 23 of elec tromagnet E is carried to its extreme limit in one direction or the other, making contact when the circuit is broken with point 22, and when the resistance is cut out with point 21, the local circuit is completed through 31. c 30 Z) 29 18, and this circuit is never made or broken in any other manner and is always maintained in a responsive condition. If transmitters X and Y are set to transmit the same signals in unison, the normal condition of operation X operates to close the alarmcircuit, and Y operates to open it, while Y operates to close said circuit when X operates to open it. As shown in the drawings, the foot 14L of transmitter X, when riding on aprojection, cuts out resistance R", and the contact 23 engages the contact 19, closing the alarm-circuit at that point. Coincidently the foot 39 of transmitter Y, riding on a projection, breaks the alarm-circuit at 34-. -When the foot 14 of transmitter X falls to the periphery of the wheel, resistance R is cut into circuit and the contact 23 engages with contact 20. If during this time the tooth (50 of Y has reached the tooth 40 on the foot 39, the alarmcircuit is closed at 38 and an alarm is sounded. If, however, the transmitters are in unison, as shown in Fig. l, the circuit will remain open at 38. If the foot 39 of transmitter Y rides between the teeth and 51, the alarmcircuit will be closed at 34; but during this time the foot 1% of transmitter X, if said transmitter is in unison, will be in position between the teeth 50 and 51, R will be in circuit, and the alarm-circuit will be closed at 20 23 and open at 38 and 19. If, however, X is out of unison and the foot let of X should be riding upon a tooth or projection, the alarm-circuit would be closed at both 19 and 34, and an alarm would sound.

I have arranged a switch in the local or alarm circuit to provide for conditions of the protected premises and circuits existing during the time the safe or protected structure is not under the care of the watchman at the central station, and I have added electrical connections in said circuit, controlled by said switch, so arranged that the act of closing the safe or protected structure will sound an alarm intended to notify the watchman that the structure is again placed under his care, when he will assume charge and change the switch to operate the local or alarm circuit in accordance with the co-operative plan hereinbefore described.

The switchlever (31 is pivoted at 54: and is capable of taking position upon points 53 or 52. A branch conductor 55 connects the point 52 with the conductor 33 and contact 19. Normally the arm 61 rests upon the contact 53 and the operation is as first described. When the safe is opened the main circuit is broken, point 23 engages point 22 and an alarm is sounded. The watchman now places switcharm 61 upon contact 52, stopping the alarm and opening its branch circuit at 53. Point 23 is separated from 19 and the alarm-circuit branch is open at that point. At the proper time and when the safe is first closed, the circuit of battery B being closed, the relay E responds, point 23 is brought into contact with point 19, and a circuit is closed Q/iCt 19, 33, 55, 52, 61, 54, c, 30, b, 29, 18, and 23, alarm 0 responds, the watchman now changes switcl1- arm 61 to point 53, and the normal operation of the two co-operating signal-transmitters is begun and continues as first above described.

What I claim, and desire to secure by Letters Patent, is-

1. The combination, in an arrangement of apparatus for protecting electrical circuits, of an electric circuit, an indicator or alarm in said circuit, a signal transmitter at one point or station operating in said circuit to produce a predetermined effect, a second signal transmitter, at a second point or station, operating said circuit to produce an effect substantially equal and opposite to the effect normally produced by said first transmitter and means for normally operating said transmitters in unison, substantially as described.

2. The combination,in an apparatus for protecting electrical circuits against unauthorized interference, of a variable signal transmitter at the protected station, an electrical circuit, an indicator or alarm in said circuit, a second variable signal transmitter, two circuit changers operated, respectively, by said transmitters one of which changes said circuit to produce a predetermined effect, the other of which changes said circuit to produce an opposite effect and means for normally operating said transmitters simultaneously, substantially as described.

' 3. The combination of two automatic signal transmitters arranged to transmit duplicate signals, a circuit changer for the first transmitter arranged to produce a predetermined effect, a circuit changer for the second transmitter arranged to produce an equal and opposite effect, electrical circuits and connections controlled by said transmitters, an indicator or alarm controlled by said circuits, and means for normally operating said circuit changers in unison whereby indication or alarm is apparent under abnormal conditions only, substantially as. described.

4:. The combination of two compound signal transmitters arranged to transmit duplicate signals, one of which breaks circuit when the other closes circuit, an electrical circuit for said transmitters, an indicator or alarm in said circuit, and means for normally operating said transmitters in unison, whereby said alarm responds only when the transmitters are out of unison, substantially as described.

5. The combination of a relay or receiving instrument, alocal circuit therefor having two or more branches, two or more contact points in said circuit, one for each branch, a contact point operated by said relay to complete said local circuit through either of said contact points, a manually operated switch in said local circuit to make the circuit of one branch and break that of the other, an alarm or indicator and a local battery common to both said branches, a main circuit containing the coils of said relay, a main battery, an artificial resistance and means for short circuiting said resistance and for opening said circuit, all arranged and operating substantially as described.

6. The combination of two automatic signal transmitters operated in unison located, respectively, at two separated stations, an electric circuit containing an alarm or indicator,

an electro magnetic relay operating circuit.

changing points in said circuit, a main electric circuit containing said relay coils, a circuit changer controlled by one of said transmitters in said main circuit and a circuit breaker controlled by the second transmitter in said alarm circuit, all arranged and operating, substantially as described.

7. The combination, at one station, of an inclosure, a main electric circuit containing an artificial resistance, a fragile section of conductor and circuit closing points in proximity, connected to opposite sides of said resistance, a relay in said main circuit at a second station, responsive to breaks and variations of current in said circuit, a local circuit con trolled by said relay, an indicator or alarm in said circuit and two automatic transmitters located at said stations, respectively, and operating in unison to control said alarm circuit, substantially as described.

8. The combination, at one station, of an electric circuit, an alarm or indicator in said circuit, a relay having circuit closing points in said circuit, a second circuit closer in said circuit, an automatic signal transmitter to operate said circuit closer, a main circuit containing the coils of said relay and at a second station an artificial resistance, a circuit closer to cut in and out said resistance, and an automatic signal transmitter to operate said circuit closer, substantially as described.

9. The combination, at one station, of an electric circuit, an alarm or indicator in said circuit, a relay controlling circuit closing points in said circuit, a second circuit closer in said circuit,an automatic signal transmitter to operate said circuit closer, a main circuit containing the coils of said relay, an artificial JOHN M. ORAM. Witnesses:

ED. T. MOORE, J GEN FROST. 

